1. Field of the Invention
The present invention relates generally to digital information and data storage and, more specifically, to systems and devices for changing portable data storage modules, described in an exemplary embodiment for magnetic tape storage devices for computer applications.
2. Description of the Related Art
From the start, digital computers have required some form of data storage as an adjunct to their relatively sparse main memory facilities (typically random access memory (RAM) integrated circuits).
Most personal computers use a "hard disk," sometimes referred to as a Winchester disk, for on-line storage of many millions of bytes of software programs and user created data.
It is well-known that flexible disks and disk drive systems provide a common system for backing up the hard disk in case of a catastrophic failure making access impossible or fruitless. Other examples of such storage methods include optical disks, changeable hard disks (known as "Bernoulli disks"), and magnetic tape drives, using standard cassettes, computer cartridges such as the popular 3M ANSI-standard DC600 cartridge and DC2000 mini-cartridge ("3M" is a trademark of Minnesota Mining and Manufacturing Company). Each of these medium lend themselves to loading into multi-unit magazines.
Magnetic tape devices have come to the forefront as fast, efficient, economical means for storing computer data, such as for backing-up hard disk software application programs and user data created using the programs or for off-line file management tasks routinely implemented between a disk and tape as the data is processed. These devices are available for storing data in capacity ranges that match the requirements of small to medium computer systems. For example, commercially available devices can magnetically store up to 320 megabytes of digital data on quarter-inch tape cartridges. A detailed description of well known computer tape drive technology can be found in STREAMING, Copyright 1982, Archive Corporation, Library of Congress Catalog No. 82-072125.
These various types of digital data storage media are referred to generically as "data storage modules" hereinafter. The apparatus for using such a module will be referred to generically as a "drive" regardless of the media for which it is adapted. While this application will focus on computer back-up tape cartridges as a prime exemplary embodiment, it will be obvious to a person skilled in the art that the present invention is applicable to all other data storage modules adaptable to multi-module magazine loading, including modules used for non-computer data, such as audio CD's and CD-ROMS.
As computer hard disk memories grow, as the size of the stored information expands (e.g., technical drawings use vast amounts of memory), or as personal computers become "networked," the need for a fast, reliable means for storing vast amounts of data generally exceeds the capacity of a single data storage module. Hence, there is a need for changing data storage modules in order to increase the peripheral storage capacity of the computer or computer network. Preferably, such loaders, or data storage module changers, are designed to operate without human manipulation of the module.
A typical cartridge loader of the prior art is shown in U.S. Pat. No. 4,918,548 (O'Donnell et al.). A large and complex mechanism for pushing a cartridge into a drive or gripping and pulling a cartridge out of the drive is shown.
Co-pending applications of the common assignee of the present invention, U.S. Ser. Nos. 07/434,036 (filed Nov. 9, 1989) and its continuation-in-part 07/510,548 (filed Apr. 18, 1990), disclose a compact system which can be affixed directly to a drive in a personal computer meeting industry standard "form factors" (also called "5 1/4 inch" or "3 1/2 inch drives"). Said applications further disclose a means for selectively registering modules in a magazine with the module loading aperture of a drive. Said applications are incorporated herein by reference.
There is a need for a cartridge loader/changer which reduces the complexity of known systems and provides increased reliability.